There is still one thing beyond me. What about..
$foo;
What purpose does it serve being able to do that. As I said before all I can think it would be good for is as a return for a sub. (I really need to get some books dont I)
I'm just curious :)

That doesn't do anything at all; you're introducing a value into a null context. That is, your statement has no effect whatsoever since there are no side effects. For instance, try the one-liner perl -we "$_;"Using the -w flag will let you know when your statements aren't doing anything.

Ok, so if it does nothing, then why not in a future perl release allow that to assign the value to $_. Sure it might sound completely useless, but if it already is useless. I would find something like that very handy. As for making sense, it seems to do that too..